[simpleman1025]

I bought an older home that has been pretty much jack legged over the years.
I had a friend who owns an HVAC business come over and look over the units. He added a little refrigerant to one and ran them, everything checked out ok. Of course it wasn't needed at the time last month. Last week I started running them and low and behold both units started short cycling. My friend can't make it being we're 3 hours away and it seems when we call people/businesses that are recommended in our new area, they don't call back or come over.

So here we are, Ive googled causes of short cycling and started through the process of elimination. Refrigerant level is good it was checked this week, returns are clear, thermostat is in a central location, unit is not oversized. I thought maybe the capacitors were a little off so I changed them out. I also noticed that the blower fan was not spooling up to what it was previously. I hate to think this but my friend had a former relative that he trained that works in the area come by and check it out. He came up with it being the blower motor needs replacing. He quoted me on a new unit $6300.00. Knowing this person from the past the wife doesn't trust him. So I started more research and found the DIP switches were not set properly. Motor is spooling up just fine now...

Trust me when I say I'm not trying to replace any techs by no means but now a week has passed and I guess they have enough work so I'm kind of stuck.

Any help or direction to look would be greatly appreciated.






I'm not an HVAC tech but I have a background in electrical processes

 

[user_12345a]

what do you mean by short cycling?

 

[simpleman1025]

The condenser unit turning off and on every 30 seconds to a minute

 

[roughneck]

Does the unit have pressure switches?
I’d say they are likely low on charge or overcharged.

 

[simpleman1025]

The charge is good, pressure builds rapidly when the compressor starts, builds to around 600psi then drops off at the overpressure. Something is not opening allowing pressure to equalize.

 

[bfrabel]

The charge is good, pressure builds rapidly when the compressor starts, builds to around 600psi then drops off at the overpressure. Something is not opening allowing pressure to equalize.

That description is the exact opposite of "the charge is good".

Your indoor blower would have nothing to do with the pressure getting to 600psi. The problem lies somewhere in the high pressure side of the system, which is basically the outside portion of the system. Either it's way overcharged, the condenser is dirty, the condenser fan isn't working correctly, there's air or something else mixed in with the refrigerant, or a combination of those things.

It could also be a restriction inside of the condenser, but that's kind of rare. I guess it could also be a problem with the indoor section which would cause low pressure, which might have led the last guy to way overcharge it.

You need to find someone who knows what the hell they are doing, which seems to be your biggest problem at this point. Please let us know if someone figures it out. Good luck!

 

[roughneck]

The charge is good, pressure builds rapidly when the compressor starts, builds to around 600psi then drops off at the overpressure. Something is not opening allowing pressure to equalize.

That’s going off on high pressure. Something is wrong with the charge. R410A high pressure switches usually open at 600.

 

[simpleman1025]

You are correct when you say " find someone that K
knows what the hell they're doing". Like I said, I've called multiple companies however they have yet to show up or even answer when I call them again, I don't understand it that is why I'm trying to figure it out

 

[roughneck]

The condenser is dirty, there is a restriction, the condenser fan isn’t working right or they are overcharged. Or a combination of all of those.
The one your buddy added refrigerant to, where did he find the leak at?

 

[surferdude2]

Since you obviously have a gauge manifold or at least a high side gauge and hose, it's likely that you may also have a jug of gas. If that be so, you may have overcharged that system or both systems.

You're faced with getting someone to withdraw some of the refrigerant and test to see that the system works after that. You can't easily do that yourself without going to a lot of trouble setting up a cold jug system with a tub of icy slush water and migrating some charge from the system back to the refer jug. Dry ice works well too... lots of fun. The downside is, if your system is contaminated, you'll also contaminate your jug.

I presume the king valve isn't closed. lain:

 

[simpleman1025]

Surferdude, like I said I'm no HVAC tech. I'm just someone that can't seem to get a recommended tech to call back or show up. I guess it was to close to the weekend...lol. No worries, I've been researching and trying to solve it while waiting for someone that needs business to call me back. My friends former relative that works nearby put his gauges on it said that all looks good and wanted to change just about everything. Thats not much trouble shooting more like a parts changer, hell I can do that...lol

News Flash a local tech that I called this morning called me back...yay!

What gets me is that only the downstairs unit was recharged with refrigerant but both are doing the same damn thing "short cycling". The only thing in common recently is my friend changed out the thermostats. They're brand new and I even jumped the yellow to the red on the downstairs thermostat and it still would short cycle.

One more question, I have two units. there is more square footage downstairs but there is a 2 1/2 ton for downstairs and upstairs has a 3 ton with less square footage. Shouldn't the larger unit be for more square footage?

 

[roughneck]

Equipment isn’t sized via square footage. It’s sized via space and heat load.
Are the condensers dirty? Condenser fans running?
If the unit needed to be charged you need to find and fix the leak.

 

[surferdude2]

The square footage is only one part of a heat load calculation, and not the main one at that. Generally the upper story heat load is higher.

Perhaps your friend's former relative got air and moisture in your systems and they are freezing up at the metering device and pumping down.